CVE-2026-78980 in Chrome
Summary
by MITRE • 08/26/2026
Improper input validation in ReaderMode in Google Chrome prior to 152.0.7977.65 allowed a remote attacker leveraging social engineering to bypass web origin policy into a privileged page via a crafted HTML page. (Chromium security severity: Low)
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Analysis
by VulDB Data Team • 08/26/2026
The vulnerability identified as an improper input validation flaw within the ReaderMode feature of Google Chrome prior to version 152.0.7977.65 represents a significant breach in web origin policy enforcement. This specific component, designed to extract and display readable content from complex web pages, failed to adequately sanitize or validate inputs under certain conditions. The core technical flaw lies in the insufficient checks performed on data processed by ReaderMode, which allowed crafted HTML structures to manipulate how the browser interpreted document boundaries. By exploiting this weakness, an attacker could trick a user into loading a maliciously constructed webpage that leverages social engineering tactics to gain unauthorized access to privileged pages or contexts within the browser environment. This bypass of origin policies undermines one of the fundamental security models of modern web browsers, which relies on strict isolation between different origins to prevent cross-site scripting and data theft.
From an operational perspective, this vulnerability enables a remote attacker to escalate privileges within the context of the victim's browsing session without requiring any local system access or software exploits beyond the browser itself. The attack vector is primarily driven by social engineering, meaning the success of the exploit depends heavily on user interaction, such as clicking a link or visiting a compromised website that hosts the crafted HTML page. Once triggered, the malformed input allows the attacker's content to interact with privileged resources in ways that should be restricted by same-origin policies. This can lead to unauthorized access to sensitive data stored within those pages, potential session hijacking if cookies are accessible, or further exploitation of other vulnerabilities present on the target site. The severity is classified as low because it requires user interaction and specific conditions to succeed, but its impact remains critical for any organization relying on strict web isolation for security compliance.
In terms of industry standards, this vulnerability aligns with CWE-20 Improper Input Validation, where insufficient verification allows malicious data to alter the intended behavior of a system. It also relates to CWE-79 Cross-site Scripting if the input leads to script execution in another context, and potentially CWE-862 Missing Authorization when accessing privileged resources without proper checks. From an offensive security framework perspective, this falls under ATT&CK technique T1059 Command and Scripting Interpreter if scripts are executed, or more broadly within initial access vectors that rely on user deception to bypass technical controls like origin policies. The failure here is not in the rendering engine itself but in the logical validation of content before it interacts with higher-privilege contexts.
Mitigation for this vulnerability primarily involves updating Google Chrome to version 152.0.7977.65 or later, where these input validation checks have been strengthened. Organizations should enforce automatic browser updates through group policies or endpoint management solutions to ensure all users are protected against known flaws in the rendering engine and associated features like ReaderMode. Additionally, security awareness training is crucial for end-users to recognize social engineering attempts that might lead them to visit malicious sites designed to exploit such browser-level vulnerabilities. Implementing Content Security Policy headers on web applications can also provide an additional layer of defense by restricting how content from different origins interacts with the page, thereby reducing the impact if a similar vulnerability were present in other browsers or future versions. Regular auditing of third-party extensions and plugins is also recommended as they may interact with browser APIs in ways that could exacerbate such input validation issues.